Measurement of the Inclusive Jet Cross Section with the ATLAS Detector at the Large Hadron Collider

Measurement of the Inclusive Jet Cross Section with the ATLAS Detector at the Large Hadron Collider
Author: Caterina Doglioni
Publisher: Springer Science & Business Media
Total Pages: 167
Release: 2012-07-28
Genre: Science
ISBN: 3642305385

Tests of the current understanding of physics at the highest energies achievable in man-made experiments are performed at CERN’s Large Hadron Collider. In the theory of the strong force within the Standard Model of particle physics - Quantum ChromoDynamics or QCD - confined quarks and gluons from the proton-proton scattering manifest themselves as groups of collimated particles. These particles are clustered into physically measurable objects called hadronic jets. As jets are widely produced at hadron colliders, they are the key physics objects for an early "rediscovery of QCD". This thesis presents the first jet measurement from the ATLAS Collaboration at the LHC and confronts the experimental challenges of precision measurements. Inclusive jet cross section data are then used to improve the knowledge of the momentum distribution of quarks and gluons within the proton and of the magnitude of the strong force.

The Black Book of Quantum Chromodynamics — A Primer for the LHC Era

The Black Book of Quantum Chromodynamics — A Primer for the LHC Era
Author: John Campbell
Publisher: Oxford University Press
Total Pages: 761
Release: 2018-01-19
Genre: Science
ISBN: 0191014990

The Black Book of Quantum Chromodynamics is an in-depth introduction to the particle physics of current and future experiments at particle accelerators. The book offers the reader an overview of practically all aspects of the strong interaction necessary to understand and appreciate modern particle phenomenology at the energy frontier. It assumes a working knowledge of quantum field theory at the level of introductory textbooks used for advanced undergraduate or in standard postgraduate lectures. The book expands this knowledge with an intuitive understanding of relevant physical concepts, an introduction to modern techniques, and their application to the phenomenology of the strong interaction at the highest energies. Aimed at graduate students and researchers, it also serves as a comprehensive reference for LHC experimenters and theorists. This book offers an exhaustive presentation of the technologies developed and used by practitioners in the field of fixed-order perturbation theory and an overview of results relevant for the ongoing research programme at the LHC. It includes an in-depth description of various analytic resummation techniques, which form the basis for our understanding of the QCD radiation pattern and how strong production processes manifest themselves in data, and a concise discussion of numerical resummation through parton showers, which form the basis of event generators for the simulation of LHC physics, and their matching and merging with fixed-order matrix elements. It also gives a detailed presentation of the physics behind the parton distribution functions, which are a necessary ingredient for every calculation relevant for physics at hadron colliders such as the LHC, and an introduction to non-perturbative aspects of the strong interaction, including inclusive observables such as total and elastic cross sections, and non-trivial effects such as multiple parton interactions and hadronization. The book concludes with a useful overview contextualising data from previous experiments such as the Tevatron and the Run I of the LHC which have shaped our understanding of QCD at hadron colliders.

Physics with Electrons in the ATLAS Detector

Physics with Electrons in the ATLAS Detector
Author: Kurt Brendlinger
Publisher: Springer
Total Pages: 261
Release: 2018-01-30
Genre: Science
ISBN: 3319739301

This thesis presents two production cross-section measurements of pairs of massive bosons using final states with leptons, made with the ATLAS detector at the Large Hadron Collider. The first measurement, performed using data collected in 2012 at center-of-mass energy √ s = 8 TeV, is the first fiducial and differential cross-section measurement of the production of the Higgs Boson when it decays to four charged leptons (electrons or muons). The second measurement is the first fiducial and inclusive production cross-section measurement of WZ pairs at center-of-mass energy √ s = 13 TeV using final states with three charged leptons. A significant portion of the thesis focuses on the methods used to identify electrons from massive boson decay—important for many flagship measurements—and on assessing the efficiency of these particle identification techniques. The chapter discussing the WZ pair cross-section measurement provides a detailed example of an estimate of lepton background in the context of an analysis with three leptons in the final state.

XXII DAE High Energy Physics Symposium

XXII DAE High Energy Physics Symposium
Author: Md. Naimuddin
Publisher: Springer
Total Pages: 879
Release: 2018-05-23
Genre: Science
ISBN: 3319731718

These proceedings gather invited and contributed talks presented at the XXII DAE-BRNS High Energy Physics (HEP) Symposium, which was held at the University of Delhi, India, on 12–16 December 2016. The contributions cover a variety of topics in particle physics, astroparticle physics, cosmology and related areas from both experimental and theoretical perspectives, namely (1) Neutrino Physics, (2) Standard Model Physics (including Electroweak, Flavour Physics), (3) Beyond Standard Model Physics, (4) Heavy Ion Physics & QCD (Quantum Chromodynamics), (5) Particle Astrophysics & Cosmology, (6) Future Experiments and Detector Development, (7) Formal Theory, and (8) Societal Applications: Medical Physics, Imaging, etc. The DAE-BRNS High Energy Physics Symposium, widely considered to be one of the leading symposiums in the field of Elementary Particle Physics, is held every other year in India and supported by the Board of Research in Nuclear Sciences (BRNS), Department of Atomic Energy (DAE), India. As many as 400 physicists and researchers attended the 22nd Symposium to discuss the latest advances in the field. A poster session was also organized to highlight the work and findings of young researchers. Bringing together the essential content, the book offers a valuable resource for both beginning and advanced researchers in the field.

Electroweak Physics at the Large Hadron Collider with the ATLAS Detector

Electroweak Physics at the Large Hadron Collider with the ATLAS Detector
Author: Elodie Resseguie
Publisher: Springer Nature
Total Pages: 336
Release: 2020-11-03
Genre: Science
ISBN: 3030570169

This thesis discusses searches for electroweakly produced supersymmetric partners of the gauge and the Higgs bosons (gauginos and higgsinos) decaying to multiple leptons, using pp collisions at sqrt(s) = 13 TeV. The thesis presents an in-depth study of multiple searches, as well as the first 13 TeV cross section measurement for the dominant background in these searches, WZ production. Two searches were performed using 36.1/fb of data: the gaugino search, which makes use of a novel kinematic variable, and the higgsino search, which produced the first higgsino limits at the LHC. A search using 139/fb of data makes use of a new technique developed in this thesis to cross check an excess of data above the background expectation in a search using a Recursive Jigsaw Reconstruction technique. None of the searches showed a significant excess of data, and limits were expanded with respect to previous results. These searches will benefit from the addition of luminosity during HL-LHC; however, the current detector will not be able to withstand the increase in radiation. Electronics for the detector upgrade are tested and irradiated to ensure their performance.

Luminosity Measurement at the Compact Muon Solenoid Experiment of the LHC

Luminosity Measurement at the Compact Muon Solenoid Experiment of the LHC
Author: Olena Karacheban
Publisher: Springer
Total Pages: 153
Release: 2018-06-22
Genre: Science
ISBN: 3319931393

This book describes the application of a novel technology for beam instrumentation and luminosity measurement and first results on a cutting edge technology potentially to be used after the upgrade of the Large Hadron Collider to higher luminosity. It presents a unique diamond-based luminometer with a detailed performance study. The online bunch-by-bunch luminosity measurements provide an invaluable feedback to the Collider for beam optimisation and for the understanding of beam dynamics. The precision of the luminosity measurement is crucial for all physics analyses. This book highlights the Van der Meer method, which is used for the calibration of the luminometers of the CMS (Compact Muon Solenoid) experiment, and describes the estimate of systematic uncertainties, e.g. due to radiation damage of sensors and electronics and uncertainties of beam parameters. For the future high-luminosity upgrade of the collider, sapphire sensors are investigated in a test beam. It is demonstrated for the first time that sapphire sensors can be used as single particle detectors. A model for the charge transport in sapphire is developed and successfully applied.

Search for Exotic Mono-jet Events

Search for Exotic Mono-jet Events
Author: Valerio Rossetti
Publisher: Springer
Total Pages: 173
Release: 2015-08-24
Genre: Science
ISBN: 3319222252

This thesis describes in detail the search for new phenomena in mono-jet final states with the ATLAS experiment at the LHC. The final state is considered the golden channel in the searches for large extra dimensions (LED) but also allows access to a very rich SUSY-related phenomenology pertaining to the production of weakly interacting massive particles (WIMPS), SUSY Dark Matter candidates, GMSB SUSY models with very light gravitino masses, as well as stop an sbottom pair production in compressed scenarios (with nearly degenerated squarks and the lightest neutralino), and also invisible Higgs searches, among others. Here, a number of these scenarios are explored. The measurements presented yield new powerful constraints on the existence of extra spatial dimensions, the pair production of WIMPs, and also provide the best limit to date on the gravitino mass.

Physics for Particle Detectors and Particle Detectors for Physics

Physics for Particle Detectors and Particle Detectors for Physics
Author: Philipp Windischhofer
Publisher: Springer Nature
Total Pages: 243
Release: 2023-10-02
Genre: Science
ISBN: 3031390555

Experimental particle physics is a science of many scales. A large number of physical processes spanning energies from meV to TeV must be understood for modern collider experiments to be designed, built, and conducted successfully. This thesis contributes to the understanding of phenomena across this entire dynamic range. The first half of this document studies aspects of low-energy physics that govern the operation of particle detectors, limit their performance, and guide the development of novel instrumentation. To formalise these aspects, classical electrodynamics is used to derive a general description of the formation of electrical signals in detectors, and ideas from quantum mechanics are applied to the study of charge avalanche amplification in semiconductors. These results lead to a comprehensive analytical characterisation of the time resolution and the efficiency of single-photon avalanche diodes, and isolate the most important design variables. They also reveal the applicability of these devices in precision timing detectors for charged particles, which is experimentally verified in a high-energy hadron beam. Large detector systems at hadron colliders probe fundamental physics at the energy frontier. In the second half, data collected with the ATLAS detector during Run 2 of the Large Hadron Collider are used to measure the cross-section for the production of a Higgs boson together with an electroweak boson as a function of the kinematic scale of the process. This measurement provides the finest granularity available to date for this process. It is highly informative of the structure of interactions beyond the direct kinematic reach of the experiment, and new limits are set on the couplings of such interactions within an effective field theory.

Computer Simulation Validation

Computer Simulation Validation
Author: Claus Beisbart
Publisher: Springer
Total Pages: 1056
Release: 2019-04-09
Genre: Computers
ISBN: 3319707663

This unique volume introduces and discusses the methods of validating computer simulations in scientific research. The core concepts, strategies, and techniques of validation are explained by an international team of pre-eminent authorities, drawing on expertise from various fields ranging from engineering and the physical sciences to the social sciences and history. The work also offers new and original philosophical perspectives on the validation of simulations. Topics and features: introduces the fundamental concepts and principles related to the validation of computer simulations, and examines philosophical frameworks for thinking about validation; provides an overview of the various strategies and techniques available for validating simulations, as well as the preparatory steps that have to be taken prior to validation; describes commonly used reference points and mathematical frameworks applicable to simulation validation; reviews the legal prescriptions, and the administrative and procedural activities related to simulation validation; presents examples of best practice that demonstrate how methods of validation are applied in various disciplines and with different types of simulation models; covers important practical challenges faced by simulation scientists when applying validation methods and techniques; offers a selection of general philosophical reflections that explore the significance of validation from a broader perspective. This truly interdisciplinary handbook will appeal to a broad audience, from professional scientists spanning all natural and social sciences, to young scholars new to research with computer simulations. Philosophers of science, and methodologists seeking to increase their understanding of simulation validation, will also find much to benefit from in the text.

Search for Higgs Boson Pair Production in the bb̅ τ+ τ- Decay Channel

Search for Higgs Boson Pair Production in the bb̅ τ+ τ- Decay Channel
Author: Luca Cadamuro
Publisher: Springer
Total Pages: 283
Release: 2018-12-06
Genre: Science
ISBN: 3030040550

This thesis presents innovative contributions to the CMS experiment in the new trigger system for the restart of the LHC collisions in Run II, as well as original analysis methods and important results that led to official publications of the Collaboration. The author's novel reconstruction algorithms, deployed on the Field-Programmable Gate Arrays of the new CMS trigger architecture, have brought a gain of over a factor 2 in efficiency for the identification of tau leptons, with a very significant impact on important H boson measurements, such as its decays to tau lepton pairs and the search for H boson pair production. He also describes a novel analysis of HH → bb tautau, a high priority physics topic in a difficult channel. The original strategy, optimisation of event categories, and the control of the background have made the result one of the most sensitive concerning the self-coupling of the Higgs boson among all possible channels at the LHC.